0     8     16    24    32    40    48    56
+-----+-----+-----+-----+-----+-----+-----+-----+
|                 EXPIRATION                    |
+-----+-----+-----+-----+-----+-----+-----+-----+
|    SIZE   |    FLAGS  |        TYPE           |
+-----+-----+-----+-----+-----+-----+-----+-----+
|                      DATA                     /
/                                               /
/                                               /
+-----+-----+-----+-----+-----+-----+-----+-----+
|                   EXPIRATION                  |
+-----+-----+-----+-----+-----+-----+-----+-----+
|    SIZE   |    FLAGS  |        TYPE           |
+-----+-----+-----+-----+-----+-----+-----+-----+
|                     DATA                      /
/                                               /
+-----+-----+-----+-----+-----+-----+-----+-----+
|                     PADDING                   /
/                                               /
+-----+-----+-----+-----+-----+-----+-----+-----+